Yes, I think that's an element, too. School-age kids are very susceptible to peer pressure. At that age, peers are more important than family. So parents who care about education are naturally reluctant to send their kid to a school where a lot of kids don't value education.

And yes, crime is an issue, too. I never went to the bathroom when I was at school. I wouldn't drink anything all day, so I didn't have to. If you went into the bathroom at a rural or city school, they'd beat you up and take your lunch money. This generally wasn't a problem in suburban schools. Oh, they were just as mean, and just as into drugs, but they had enough money that they didn't have to beat up younger kids for loose change. (My mom used to sew secret pockets into my clothes, so I could hide my lunch and bus money.)